Rotary pump



April 28, 1931. T. w. NICHOLS ROTAR P Filed M 16' 1929 4 3 I H w I a 2 l 9 W w B Q77 A 9 1 W 3 1 w m w y 5 .4 4 2 m F M45 MCHQLS I Patented Apr. 28, 1931 UNITED STATES PATENT: OFFICE THOMAS WINTER NICHOLS, OF LONDON, ENGLAND ROTARY PUMP 7 Application filed May 16, 1929, Serial No. 363,555, and'inereat Britain May 24, 1928.

This invention relates to improvements in rotary pumps, compressors and the like of the type in which a star or tooth wheel rotor is revoluble eccentrically within a cylindri- 5 cal casing and in mesh with a concentrically revoluble ring of teeth or abutments, there being interposed between the rotor and the ring at a position opposite the point of mesh of the rotor and the ring a block in the form of a crescent or a portion of a crescent, the concavity of such crescent coinciding with an arc of the circle of revolution of the tips of the lobes of the star rotor and the convexity with an arc of the circle of revolution of the inwardly directed tips of the teeth or abutments of the ring rotor.

In pumps of this kind various attempts have been made to improve the working by particular shapes given to the contacting teeth of the rotor and the ring and the object of my invention is to provide a construction and arrangement of the contacting teeth which will provide for a thoroughly efiicient working while giving great strength to the teeth and prevent any possibility of shearing the shaft which is liable to occur in pumps or compressors of the known kind when dirt or foreign matter becomes lodged between the top and bottom of the teeth when the rotor and the ring are revolving at high speed. V

The annexed drawings illustrate an example of construction of my improved pump.

Fig. 1 is a transverse section and Fig. 2 a longitudinal section of the apparatus.

In the example illustrated 1 indicates the rotor, 2 the ring, 3 the crescent shaped member and 4 the pump casing.

The teeth 1a of the rotor 1 may be formed 40 on or attached to a central web 5 of a sleeve 6 forming the hub of the rotor and keyed to the pump shaft 6a. Between the sleeve 6 and the bottoms of the teeth 1a are two rings 7 formed on two sleeves or bearing bushes 7a fixed in the side walls of the casing these rings fitting in the spaces between the bottoms of the teeth and the sleeve 6 and abutting against the sides of the web 5 and the ends of this sleeve as shown in Fig.

50 2, the whole forming a strong construction with the rotor running in a track formed by said bearing bushes, as described, the casing 4 and the crescent 3. The ring 2 may be formed of two similar sized annular mem bers 9 connected by bars forming teeth 10, the whole thus constructed rotating with the members 9 in annular recesses 11 in the casing walls and the teeth 10 in the track 11a formed by the casing and the outer surface of the crescent while being driven by the rotor 1. I 7 I The teeth 1a of the rotor are of considerable widthxfor instance if there are four of these teeth they would each occupy along a circumference passing through their mid oints a circumferential distance equal to about one eighth the total circumference of the circle passing through these points the outer surfaces12 being curved to a circumference contacting with the concave surface 13 of the crescent. V

'Theteeth or abutments of the ring (of which in the'case' of four teeth "on the rotor there may be siX as shown in Fig. 1) are of similar width to the teeth of the rotor; and their inner surfaces are curved to a circumference 14 coinciding with the curved surface 15 of'the crescent.

By means of the'wide teeth of the rotor and the ring I obtain good packing and prevent or, minimize to a large extent leakage, since I also obtain wide circumferentialcontact surfaces whereas with ordinary shaped gear teeth only what might be termed point contact can be obtained for circumferential contact. 1

Further these wide teeth and the method of constructing the rotor and the ring and the method of mounting the same give great strength to the whole while providing for most efiicient action and smooth running of the parts. 7

The flanks of the teeth of the rotor (which in the case of a Water or oil-pump are the only actual surfaces of the teeth contacting one with the other) may be curved as shown in Fig. 1 to circles having as centres the centres of the teeth taken on the circumferences passing through their mid points but these edges may, however have any other suitable shape which would facilitate machining on a gear cutting machine. I

The crescent shaped member 3 is recessed, as at 3a the recessed portion forming a suc- 5 tion passage for the rotor.

The aparatus is provided with the usual inlet 16 and outlet 17 and operates in the usual manner. I I

In the case for instance where the pump is to be used for heavy oils I may provide an additional inlet this being a lateral inlet passing through the side walls of the casing and having openings adjacent the side I of the rotor 1 as shown at 18 in Fig. 1.

Further I may provide the flanks 19 of the teeth 1a of the rotor 1 with small channels extending from the bottoms to the tops of these teeth and also I may provide the teeth of the ring 2 with perforations as at 20 20 in Fig. 1, these channels and perforations allowing the escape of any liquid. which might come between the teeth.

What I claim as my invention and desire to secure by Letters Patent of the United States is In a rotary pump comprising a toothed rotor in mesh with a revoluble ring of teeth and having a crescentvshaped block between the rotor and the ring the combination of a 0 sleeve keyed to the pump shaft, a web formed centrally on said sleeve, bars connected to said web transversely there-to, arranged parallel to one another and to the pump shaft, and having wide outer andinner surfaces,

and fixed bearingbushes between the outer surface of said sleeve and the inner surfaces of said bars, the outer surfaces of the bars contacting when the pump is working with the pump casing and the crescent shaped 40 block over the whole of their length and width and the inner surfaces of the bars contacting with the bearing bushes over the whole of their width and of their length with the exception of that part occupied by the connection'of the bars to theweb all substantially as set forth.

In witness whereof I have signed this specification.

THOMAS WINTER NICHOLS; 

